Murine dorsal root ganglion (DRG) neurons grown in primary dissociated cell culture have mu-, delta- and kappa- opioid receptors on their somatic surfaces. Mu- and delta- opioid receptors are coupled to a voltage and/or calcium-dependent potassium conductance while kappa- opioid receptors are coupled to a voltage-dependent calcium channel. In addition, opioid receptors are coupled to adenylate cyclase. Binding of opioids to opioid receptors results in the activation of the inhibitory GTP-binding regulatory protein, GI, resulting in an inhibition of adenylate cyclase and thus to a reduction of intracellular cyclic AMP concentration. Furthermore, binding of opioids to their receptors is regulated by guanine nucleotides. In the present application, we propose to investigate the coupling of opioid receptors to their ion channels. First, we propose to characterize the specific potassium channel which is enhanced by mu- and delta- opioid receptor activation. Second, we intend to characterize the calcium channel which is inhibited by kappa-opioid receptor activation. Third, we intend to determine whether or not the coupling between mu-, delta- and kappa- opioid receptors is via a second messenger system, specifically the adenylate cyclase/cyclic AMP system. We will use intracellular recording, voltage clamp and patch clamp techniques to characterize whole cell currents and single channel currents in this project.